1. Field of the Invention
The present invention relates generally to Ethernet expansion, and in particular, to a bridge-based Radio Access Station (RAS) backbone network that forms the backbone of a wireless system by the Ethernet technology, and a signal processing method therefor.
2. Description of the Related Art
Ethernet is one of the most prevalent network technologies for Local Area Networks (LANs). Due to its universality and simple structure, the application of Ethernet extends its use to Very Local Area Networks (VLANs) and Wide Area Networks (WANs).
FIG. 1 illustrates the configuration of a conventional Wireless Broadband (WiBro) RAS backbone network. As shown, the WiBro RAS backbone network includes a plurality of RASs 10 and Access Control Routers (ACRs) 12 for controlling the RASs 10. The WiBro network may further include a Home Agent (HA, not shown) for supporting the Internet Protocol (IP) mobility of a Customer Equipment (CE) and an Authentication, Authorization, and Accounting (AAA) server 14 for authenticating users and CEs, verifying authorization, and billing to provide network connectivity and services to authorized users only.
Each of the RASs 10 has an allocated service area, i.e. a cell and provides services to a plurality of CEs 11, for example, portable phones, Personal Digital Assistants (PDAs), and laptops, within the cell. The RAS 10 sends and receives signals to and from the CEs 11 on radio channels. The RAS 10 is connected to an ACR 12 forming an IP subnet via a wired channel. The RAS 10 encapsulates a radio signal received from a CE 11 in an IP packet and sends the IP packet to an upper-layer ACR 12′. The ACR 12′ delivers the IP packet to a neighbor ACR 12″ near to a recipient by switching according to the IP address of the recipient. In this way, communications are conducted by IP packets, and the recipient is located by his IP address in the conventional RAS backbone network.
As illustrated in FIG. 1, the conventional RAS backbone network is configured mainly using Layer 3 (L3) routers. Thus, the network configuration is rather complex and its management is not efficient. Moreover, since a handover occurs in L3, the handover takes a long time.